1. Field of the Invention
The present invention relates to an air conditioning system, and more particularly to a system for circulating a fluid which can change a phase between a gas phase and a liquid phase by a difference of a specific gravity between a gas phase and a liquid phase between a heat source side machine and a plurality of user side machines disposed below the heat source side machine, so that each of the user side machines can at least perform a cooling operation.
2. Background Art
Conventional arts include, for example, a system as shown in FIG. 7 as an air conditioning system which does not need a power for transporting a phase-changeable fluid, that is, a fluid changing a phase between a liquid phase and a gas phase by outputting or inputting a latent heat. In this system, a heat source side machine 1 serving as a condenser is mounted at a high position of a building, and a liquid phase pipe 6 and a gas phase pipe 7 connect the heat source side machine with a heat exchanger 5 of an user side machine 4 mounted in a room to be air-conditioned disposed in a lower position than the heat source side machine. The system supplies a liquid which is heat-discharged and condensed by the heat source side machine 1 to the heat exchanger 5 of the user side machine 4 through the liquid phase pipe 6 by its own weight and on the contrary returns a gas which is heat-absorbed and evaporated by heat-exchanging with a warm air in the room by the heat exchanger 5 of the user side machine 4 to the heat source side machine 1 of which pressure becomes lower by condensing of the liquid through the gas phase pipe 7, thereby capable of performing a circulation. Accordingly, there are advantages such that a transporting power such as a electric pump is not necessary and a running cost can be reduced. In this case, reference numeral 8 denotes a flow control valve and reference numeral 9 denotes a blower.
In the heat source side machine 1, the operation capacity of the heat source side machine 1 is controlled in such a manner that the temperature of the fluid discharged from the heat source side machine after condensed to the liquid phase pipe 6 is kept constant. In each of the user side machines 4, the opening ratio of the fluid control valve 8 is controlled in such a manner that the fluid supplied from the heat source side machine 1 through the liquid phase pipe 6 at a constant temperature is discharged to the gas phase pipe 7 at a predetermined temperature after being heat-exchanged with the air within the room supplied by the blower 9.
However, in the air conditioning system having the above structure, since only the weight of the fluid which discharges the heat in the heat source side machine, is condensed and is stored in the liquid phase pipe acts as a power for supplying the fluid to the user side machine, the amount of the fluid which can flow into the user side machine is limited and the fluid is super-heated in the case of large cooling load, so that the cooling performance tends to be insufficient.
Further, when the operating number of the user side machines is changed, or the temperature difference of the fluid flowing into or discharging out of the user side machine is changed due to the change of the air conditioning load within the room, or the opening ratio of the flow control valve is changed, the operating performance of the heat source side machine is not changed immediately, but as in the same manner as the conventional manner in which the forcible circulation is performed, after recognizing the actual temperature change of the fluid discharged from the heat source side machine to the liquid phase pipe, the operating performance of the heat source side machine is controlled in such a manner that the temperature returns to a predetermined temperature. Accordingly, there is a problem that the air conditioning system is delay in replying the change of the air conditioning load. Still further, in the conventional type of air conditioning system for forcibly circulating with an electric pump, there is a problem that a quicker response with respect to the change of the air conditioning load is desired. Accordingly, there is a desire that the above problems should be solved.